docs

1 files changed, 8 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/syntax_node.rs b/crates/ra_syntax/src/syntax_node.rs
index aa627398d..a1bc0b499 100644
--- a/crates/ra_syntax/src/syntax_node.rs
+++ b/crates/ra_syntax/src/syntax_node.rs
@@ -1,3 +1,11 @@
+//! This module defines Concrete Syntax Tree (CST), used by rust-analyzer.
+//!
+//! The CST includes comments and whitespace, provides a single node type,
+//! `SyntaxNode`, and a basic traversal API (parent, children, siblings).
+//!
+//! The *real* implementation is in the (language-agnostic) `rowan` crate, this
+//! modules just wraps its API.
+
 use std::{fmt, borrow::Borrow};
 
 use rowan::{Types, TransparentNewType};